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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

25780 results found.

  1. GRB 090429D: Fermi GBM detection
  2. GRB 090429C: Fermi GBM detection
  3. GRB 090429B: Swift/UVOT Upper Limits
  4. GRB 090429A: Swift/UVOT Upper Limits
  5. GRB 090429B: Gemini-N further nIR observations
  6. GRB 090429A: Swift-XRT refined analysis
  7. GRB 090429A: GROND upper limits
  8. GRB 090427C: Fermi GBM detection
  9. GRB 090427B: Fermi GBM detection
  10. GRB 090426C: Fermi GBM detection
  11. GRB 090426B: Fermi GBM detection/observation
  12. GRB 090429B: Swift XRT refined analysis
  13. GRB 090429A: Enhanced Swift-XRT position
  14. Konus-Wind observation of very bright GRB 090427
  15. GRB 090428B: Fermi GBM detection
  16. GRB 090428: Fermi GBM detection
  17. GRB 090418A BVRcIc field calibration
  18. GRB 090429B: RIMOTS optical upper limits
  19. GRB 090429B: Enhanced Swift-XRT position
  20. GRB090429B: Gemini-N infrared IR candidate
  21. GRB 090426: YNAO-GMG observations
  22. GRB 090429B: VLT upper limits
  23. GRB 090429B: GROND Observations
  24. GRB 090429B: Super-LOTIS early observations
  25. GRB 090429B: Swift detection of a burst
  26. GRB 090429: Swift detection of a burst
  27. GRB 090424 : Multiband Optical observation from Nainital
  28. IPN triangulation of very bright GRB 090427
  29. GRB 090423: CARMA mm observations
  30. GRB 090426: Swift/BAT spectral lag results
  31. GRB 090425: Fermi GBM detection
  32. GRB 090424: Suzaku WAM observation of the prompt emission
  33. GRB 090426: VLT spectroscopy
  34. GRB 090426: GROND Observations of the Optical/NIR Afterglow
  35. GRB 090426: Okayama MITSuME optical observation
  36. GRB 090426: Swift-XRT refined analysis
  37. GRB 090423: GROND second epoch imaging and refined SED
  38. Detection of bright radio afterglow of GRB 090424 with the VLA
  39. GRB 090426: Enhanced Swift-XRT position
  40. GRB090426: Observation for Optical counterpart from MIRO
  41. GRB 090426, RIMOTS optical upper limits
  42. GRB 090426: Swift detection of a burst with an optical counterpart
  43. GRB 090424: MASTER-Net prompt optical limit
  44. GRB 090423: Fermi GBM observation (correction of isotropic equivalent energy)
  45. VLA radio observation of high-z GRB 090423
  46. GRB 090424: THO optical observations
  47. GRB 090424: GROND Observations of the Optical/NIR Afterglow
  48. GRB 090423: Y-band field calibration update/correction
  49. GRB 090423: Swift/BAT spectral lag results
  50. GRB 090424 : TAOS optical detection
  51. GRB 090424: Liverpool Telescope observations
  52. GRB 090424: Swift-XRT refined analysis
  53. GRB 090424: Optical observations from 1.23m CAHA
  54. GRB 090424: MASTER-Net prompt optical observations
  55. GRB 090424: Enhanced Swift-XRT position
  56. GRB 090424: Fermi GBM Observation
  57. GRB 090423: Fermi GBM observation
  58. GRB 090422: Fermi GBM observation
  59. GRB 090424: Swift detection of a burst with an optical counterpart
  60. GRB090423: Y-band field calibration
  61. GRB 090423 limiting magnitudes
  62. GRB 090423: Near infrared observation at Okayama Observatory
  63. GRB 090423: Deep z-band upper limit and confirmation of photo-z
  64. GRB 090423: TNG Amici spectrum
  65. GRB 090423: GROND detection and preliminary photo-z
  66. GRB 090423: NOT z-band limit
  67. GRB 090423: Swift-XRT refined analysis
  68. GRB090418A Rc-band photometry
  69. GRB 090423: NIR photometry and evidence for spectral break
  70. GRB 090422: Swift-XRT refined analysis
  71. GRB090423, RIMOTS optical upper limits
  72. GRB 090423: Enhanced Swift-XRT position
  73. GRB 090423: Swift-BAT refined analysis
  74. GRB 090422: Swift/UVOT Upper Limits
  75. GRB 090423: UKIRT K-band observations
  76. GRB 090423: P60 Observations
  77. GRB 090423: Faulkes Telescope South observations
  78. GRB 090418A: R and I band observation
  79. GRB 090423: Swift detection of a burst
  80. GRB 090418A: Konus-Wind and Swift/BAT joint spectral analysis
  81. GRB 090422: Enhanced Swift-XRT position
  82. GRB 090418B: RTT150 optical observations
  83. GRB 080410: GAO 150cm telescope Optical Observation
  84. GRB 080408A: GAO 150cm telescope Optical Observation
  85. GRB 090422: Liverpool Telescope observations
  86. GRB 090422: Swift detection of a burst
  87. GRB 090418C: Fermi GBM Detection
  88. GRB 090418B: GRAS002 observatios
  89. GRB 090418B: GROND observations
  90. GRB 090419: Swift/UVOT Observations
  91. GRB 090418B: Faulkes Telescope North observations
  92. GRB 090418A: Swift/UVOT Observations
  93. GRB 090417B: Swift/UVOT Upper Limits
  94. GRB 090419: Swift-XRT refined analysis
  95. Konus-Wind observation of GRB 090418B
  96. GRB 090419: GROND detection of afterglow candidate
  97. GRB 090418: Optical observations with MITSuME Okayama and Ishigaki 1m telescope
  98. VLA radio detection of GRB 090418
  99. VLA radio upper limit on GRB 090417B
  100. GRB 090419: Enhanced Swift-XRT position

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